/*
20080913
D. J. Bernstein
Public domain.
*/

#include <stdint.h>

typedef uint64_t uint64;

extern int crypto_hashblocks_sha512(unsigned char *statebytes, const unsigned char *in, unsigned long long inlen);

#define blocks crypto_hashblocks_sha512

static const unsigned char iv[64] = {
        0x6a, 0x09, 0xe6, 0x67, 0xf3, 0xbc, 0xc9, 0x08,
        0xbb, 0x67, 0xae, 0x85, 0x84, 0xca, 0xa7, 0x3b,
        0x3c, 0x6e, 0xf3, 0x72, 0xfe, 0x94, 0xf8, 0x2b,
        0xa5, 0x4f, 0xf5, 0x3a, 0x5f, 0x1d, 0x36, 0xf1,
        0x51, 0x0e, 0x52, 0x7f, 0xad, 0xe6, 0x82, 0xd1,
        0x9b, 0x05, 0x68, 0x8c, 0x2b, 0x3e, 0x6c, 0x1f,
        0x1f, 0x83, 0xd9, 0xab, 0xfb, 0x41, 0xbd, 0x6b,
        0x5b, 0xe0, 0xcd, 0x19, 0x13, 0x7e, 0x21, 0x79
};

int crypto_hash_sha512(unsigned char *out, const unsigned char *in, unsigned long long inlen) {
    unsigned char h[64];
    unsigned char padded[256];
    int i;
    unsigned long long bytes = inlen;

    for (i = 0; i < 64; ++i) h[i] = iv[i];

    blocks(h, in, inlen);
    in += inlen;
    inlen &= 127;
    in -= inlen;

    for (i = 0; i < inlen; ++i) padded[i] = in[i];
    padded[inlen] = 0x80;

    if (inlen < 112) {
        for (i = inlen + 1; i < 119; ++i) padded[i] = 0;
        padded[119] = bytes >> 61;
        padded[120] = bytes >> 53;
        padded[121] = bytes >> 45;
        padded[122] = bytes >> 37;
        padded[123] = bytes >> 29;
        padded[124] = bytes >> 21;
        padded[125] = bytes >> 13;
        padded[126] = bytes >> 5;
        padded[127] = bytes << 3;
        blocks(h, padded, 128);
    } else {
        for (i = inlen + 1; i < 247; ++i) padded[i] = 0;
        padded[247] = bytes >> 61;
        padded[248] = bytes >> 53;
        padded[249] = bytes >> 45;
        padded[250] = bytes >> 37;
        padded[251] = bytes >> 29;
        padded[252] = bytes >> 21;
        padded[253] = bytes >> 13;
        padded[254] = bytes >> 5;
        padded[255] = bytes << 3;
        blocks(h, padded, 256);
    }

    for (i = 0; i < 64; ++i) out[i] = h[i];

    return 0;
}
